Wikipedia
Koorde
In peer-to-peer networks, Koorde is a Distributed hash table (DHT) system based on the Chord DHT and the De Bruijn graph ( De Bruijn sequence). Inheriting the simplicity of Chord, Koorde meets O(log n) hops per node (where n is the number of nodes in the DHT), and O(log n/ log log n) hops per lookup request with O(log n) neighbors per node.
The Chord concept is based on a wide range of identifiers (e.g. 2^160) in a structure of a ring where an identifier can stand for both node and data. Node-successor is responsible for the whole range of IDs between itself and its predecessor.